Thank you very much.
I wrote a program that tests all opcodes (including the undocumented ones) and record the execution on a Z84C0010AEG
All the observed patterns are the following
[('rd',),
('rd', 'rd'),
('rd', 'rd', 'rd'),
('rd', 'rd', 'rd', 'rd'),
('rd', 'rd', 'rd', 'rd', 'rd'),
('rd', 'rd', 'rd', 'rd', 'rd', 'rd'),
('rd', 'rd', 'rd', 'rd', 'rd', 'wr'),
('rd', 'rd', 'rd', 'rd', 'wr'),
('rd', 'rd', 'rd', 'rd', 'wr', 'wr'),
('rd', 'rd', 'rd', 'wr'),
('rd', 'rd', 'rd', 'wr', 'wr'),
('rd', 'rd', 'wr'),
('rd', 'rd', 'wr', 'wr'),
('rd', 'wr'),
('rd', 'wr', 'wr')]
I attach the list of the instructions associated to each pattern